Unexpected disappointing performance of KEF Q300 :(

[john_k_antony]

I got KEF Q300 in my dedicated HT room for my front L-C-R. 3 x KEF Q300, 1 each for L, C and R channels. I was really happy with the choice of KEF Q300 for L-C-R as Q300 delivered brilliant dialog clarity for movies. I am using Denon 2310 105w/ch to drive them.

Last couple of days, I have been cranking up the volume to pretty loud levels - 75-80% of volume level in Denon. What I have noticed is that the cones of front L-R KEF Q300 started to move very frantically during song sequences and some action sequence. Most disappointing this was that I started to hear very bad jarring sound from both L-R speakers while the cones are moving very vigorously. The jarring goes away when I turn the volume down to 70% and less. Even at very high volumes, the center channel speaker is loud and clear and doesn't move that much. I checked all my speaker cables and its polarity. Its all fine.

But I am really surprised to see the speakers running out of breath even at 75% of volume from Denon AVR which is rated at a max of 105/ch. KEF Q300 is rated for a maximum power of 120W.

I also tried setting the crossover to a very high frequency - 120Hz and still the cones were moving very vigorously. Initially it was set at 80Hz. I have set all the speakers as "Small" in the AVR. I was running the AVR in pure direct mode. I read somewhere that bass management is off during pure direct and AVR feeds the full range signal to all the speakers. But I also read that this will happen only if the speakers are set to "Large". I will try to run the same movie sequence in normal (not pure direct) mode and see if that helps.

Could this behavior due to any of the following

1. Though KEF rates Q300 to take a max load of 120W, it is not necessarily true. These speakers are designed to work with low powered stereo amps with 50w/ch output.
2. I need to chose speakers with a dedicated woofer and a separate mid range and tweeter drivers for movie watching?
3. The new Chinese made KEFs are lacking build quality??? The sound quality is very good when they are driven at a lower volume though.
4. Did I get faulty speakers?? I don't think so this is true. I will check with ProFx.

70% volume is not bad either, but I just thought of cranking the volume up for some movies and got this disappointing result.

Thanks,
John.

 

[rikhav]

I think the culprit here is the amp rather then the speakers.

It is not able to control the woofer movement and that is resulting in the jarring and other artifacts in the sound

 

[elangoas]

Did you do the speaker settings manually (or) auto calibrated with Audessey ?

What is your current speaker level settings for each speaker ? (expressed in db in AVR)

 

[argho]

I would suggest that you dont use pure direct mode.
That mode is to be used for stereo music listening, from high quality CDs.

For movies, choose one of the normal surround modes.

 

[denom]

Aha! Experienced similar situation when demo'ed the Q300's with a denon amp 710 or 20 I dont remember, will have to dig out that thread, but yes it was very surprising to see such 'vigorous' movement of the mid bass driver. Even the profx sales person was shocked to see this happen.

Song played was Pink floyd's 'Hey You' :lol:

Am going to hear some more KEF's in a short while, lets hope they do not display similar tendencies

 

[kapvin]

I got KEF Q300 in my dedicated HT room for my front L-C-R. 3 x KEF Q300, 1 each for L, C and R channels. I was really happy with the choice of KEF Q300 for L-C-R as Q300 delivered brilliant dialog clarity for movies. I am using Denon 2310 105w/ch to drive them.

Last couple of days, I have been cranking up the volume to pretty loud levels - 75-80% of volume level in Denon. What I have noticed is that the cones of front L-R KEF Q300 started to move very frantically during song sequences and some action sequence. Most disappointing this was that I started to hear very bad jarring sound from both L-R speakers while the cones are moving very vigorously. The jarring goes away when I turn the volume down to 70% and less. Even at very high volumes, the center channel speaker is loud and clear and doesn't move that much. I checked all my speaker cables and its polarity. Its all fine.

But I am really surprised to see the speakers running out of breath even at 75% of volume from Denon AVR which is rated at a max of 105/ch. KEF Q300 is rated for a maximum power of 120W.

I also tried setting the crossover to a very high frequency - 120Hz and still the cones were moving very vigorously. Initially it was set at 80Hz. I have set all the speakers as "Small" in the AVR. I was running the AVR in pure direct mode. I read somewhere that bass management is off during pure direct and AVR feeds the full range signal to all the speakers. But I also read that this will happen only if the speakers are set to "Large". I will try to run the same movie sequence in normal (not pure direct) mode and see if that helps.

Could this behavior due to any of the following

1. Though KEF rates Q300 to take a max load of 120W, it is not necessarily true. These speakers are designed to work with low powered stereo amps with 50w/ch output.
2. I need to chose speakers with a dedicated woofer and a separate mid range and tweeter drivers for movie watching?
3. The new Chinese made KEFs are lacking build quality??? The sound quality is very good when they are driven at a lower volume though.
4. Did I get faulty speakers?? I don't think so this is true. I will check with ProFx.

70% volume is not bad either, but I just thought of cranking the volume up for some movies and got this disappointing result.

Thanks,
John.

hi john,

bass handling and power handling are 2 different things. power handling is an electrical thing - which is the amount of power the voice coils can take safely. (it's also more of a guideline, for peaks you could go higher).

Bass handling is suspension driven (that's the soft part of your speaker -the cone, the spider behind the cone & the voice coil) and is a function of the cone surface area and the suspension limits of your particular woofer.

the other thing is that in bass reflex speakers, bass below the tuning frequency (of the system) is not handled gracefully. the woofer is acoustically nloaded" - so it move rapidly without producing sound, this also leads to much more rapid bottoming out (where the suspension hits the limits of it's travel)

to me it looks like your woofers are bottoming out. it is, from what you describe not an amp problem.

some questions

have you set the fronts on full? (or is there is a high pass filter?)
have you increased the bass levels?


my suggestions - use the bass management on your amp. (in any case, you speakers are rated to 42hz, so you should set your front high pass to at least 40hz). this should solve your problem.

ps. - most speaker will bottom out in the right or wrong conditions. i would be loathe to blame the amp.
let me know how it goes.

 

[doors666]

You dont have a sub, you are running pure direct, you are passing all frequencies at high volume to small bookshelf speakers, what do you expect. thank your lucky stars the woofers didnt blow. Now either tone down that volume, or make sure u dont pass very low frequencies to the speakers, or get a subwoofer.

 

[Santy]

The KEF Q300 cannot take much of bass load it seems.
Even in direct mode, the crossover settings should function.

It seems from googling that the Denon does not fully roll off the bass, but only tilts or dampens the bass below the setting.

Check if you have altered any tone controls.

You dont have a sub, you are running pure direct, you are passing all frequencies at high volume to small bookshelf speakers, what do you expect. thank your lucky stars the woofers didnt blow. Now either tone down that volume, or make sure u dont pass very low frequencies to the speakers, or get a subwoofer.

How did you conclude that he doesn't have a sub. I guess he has a Velo EQMax 12

 

[AVM]

Hi John,
I had observed this similar issue with Dentons at heliumflight's place. They were being driven by 50watt Sansui amp. He later biamped it using the speaker AB option and that resolved it making them sing .

 

[S.P.KRISHNA]

Evaluate its performance on some other AVR, Denon and other available brand at your palce.

 

[Audio_Freek]

Hi you need to run few iteration with the Speakers connecting to a different amp and check the same. I have been into such embarrassing situations before. So you could perform below checks before conclude its Kef or Denon or cable or Even source is a culprit.

1. Test the speakers with different DVD\CD with high volume.
2.Change the option to stereo mode and give a try
3.Change the source, Just identify some buddy who has powered amps, which can be tested.

But your Title has blown a shock and the time you have posted this Post makes clear that how much you love the stuff you are owing and caring you are to them. Dont worry, it could be some minor unnoticeable issue too.

 

[doors666]

How did you conclude that he doesn't have a sub. I guess he has a Velo EQMax 12

I concluded that because he's not mentioned it in his post.

 

[Santy]

I concluded that because he's not mentioned it in his post.

Well, we can't conclude, but we can always guess.

 

[reignofchaos]

It seems like the amp is clipping. Try with a decent quality integrated amp and see if it makes a difference.

 

[john_k_antony]

Friends,

Thank you very much for the excellent support and suggestions. I am delighted . I am going to do a some serious testing and A-B comparisons now. I just woke up on a lazy Sunday afternoon.

Here are some quick updates and clarifications. I am sorry I didn't make some points clear in my first post.

1. I do have a subwoofer and yes its Velodyne EQ-Max 12.

2. The speakers are set to "Small" in Denon and the cross over frequency is set to 80Hz for all speaker. As I mentioned earlier, setting the cross over to 120Hz also didnt make any difference.

3. I am using Pure Direct mode of Denon and I think they are not just for 2 channel stereo. They are meant to bypass all the digital signal processing and it is designed to work for both stereo and multi channel mode.

4. I have run Audyssey to set the speaker levels and distance. I am not using the Audyssey room correction as I already have a decently acoustically treated room.

5. I have set the channel level to +4db for front L+R and +2.5db from center. I set this levels using my SPL meter and pink tone.

I have the following gear to do some testing and comparison.

Here are the testing planned

In my dedicated room. Here I have Velodyne EqMax 12 Sub and the crossover is set at 80Hz

1. Oppo 105 - AP 70w Power amp -> KEF Q300
2. Oppo 105 - AP 70w Power amp -> KEF iQ7 (Floor stander in the same room)
3. Oppo 105 - Denon 2310 -> KEF Q300 in Pure Direct Mode
4. Oppo 105 - Denon 2310 -> KEF iQ7 in Pure Direct Mode
5. Oppo 105 - Denon 2310 -> KEF Q300 in Normal Mode
6. Oppo 105 - Denon 2310 -> KEF iQ7 in Normal Mode

In my living room. Here I have Velodyne EqMax 10 Sub and the crossover is set at 80Hz

7. Oppo 93 - Marantz 1402 -> KEF Q300 in Pure Direct Mode
8. Oppo 93 - Marantz 1402 -> KEF Q300 in Normal Mode


I will use my SPL meter as the bench mark so that I can control the volume in different amps to achieve the same SPL level at which the KEF Q300 start the vigorous cone movement.

I will try to capture the video and post the same.

Thanks once again guys for the support.

Thanks,
John.

 

[elangoas]

2. The speakers are set to "Small" in Denon and the cross over frequency is set to 80Hz for all speaker. As I mentioned earlier, setting the cross over to 120Hz also didnt make any difference.

3. I am using Pure Direct mode of Denon and I think they are not just for 2 channel stereo. They are meant to bypass all the digital signal processing and it is designed to work for both stereo and multi channel mode.

Even though you have set your speakers to "Small" & set the crossover to 80Hz, i think Pure direct mode will override all the functions and pass the full range signal to the speaker.....

My Onkyo has "Pure Audio" / Direct mode... Pure audio treats the speakers as full range even though you have set the speakers as "Small"...

 

[john_k_antony]

Friends.

Seems like I found the issue : Its the Pure Direct mode of Denon 2310 unfortunately!

I think the main reason was my misunderstanding of the functioning of pure direct mode in Denon. I assumed that Denon will use the crossover setting and bass management even in pure direct mode when the speakers are set to small. But it proved it wrong!

Here are the results of my experiments

Pre Condition

Target SPL level at listening position of 18ft from speakers : 80db

1. Oppo 105 - Denon 2310 -> KEF Q300 in Pure Direct Mode
KEF Q300 created the desired SPL level of 80 at the volume level 73 and was moving very vigorously. Here my Subwoofer was working but hardly moving or pushing any air!

2. Oppo 105 - Denon 2310 -> KEF iQ7 in Normal mode with Audyssey equilization on.
BINGO!!! I attained the SPL of 80 at a lower volume level of around 68 on the AVR and the Q300 really settled down and moving very normal. Now my Subwoofer has gone crazy . It has started to work how it should work and started punching more air and I had to reduce the level of subwoofer.

3. Oppo 105 - Acoustic Portrait Power Amp 70wch -> KEF iQ7 floor standers. Here the 5.1 signal was downmixed by Oppo 105 to its dedicated 2 channel analog out and analog out was connected to AP Power Amp.

Here everything was working normal and at the desired SPL level of 80db, everything was working perfect. Here Subwoofer was not connected and iQ7 produced decent bass.

I didn't continue my rest of testing as I think I nailed the issue.

Now the take aways

1. Denon in pure direct mode will treat all speakers are Large no matter what the setting is and send the full range signal to them. I totally agree with
elangoas on this fact. It was my bad that I "assumed" other way round .

2. Though KEF Q300 is rated to go support till 42Hz and is rated at 120W music power, I DO NOT THINK its true practically. If it was really faithful to the specifications, It shouldn't have created the jarring sound. Other sad part is that I saw some deformation and dent in the mid range cone of the Left and Right channel Q300 . I think I did some damage to the speakers due to my lack of knowledge about Denon's pure direct mode. However, the speakers are still sounding fine with the new settings. I will play it for some more time and see if needs a replacement. I will check with ProFx regarding this as my speakers are still under warranty. Denon's Audyssey also marked the Q300 as large speakers.

Final settings

1. Denon - Standard Mode with Audyssey on. No more Pure Direct mode .
2. All the speakers are set to "Small". This was already set to Small. I just reconfirmed.
3. Crossover set to 100Hz to assure that the Q300's doesn't get any damage. I already abused them, so don't want to do any more .

Here are the pictures of the damage caused to the driver. I will try to upload a video later

Right Speaker with more damage. You can see deformation and 3 dents

Center Speaker with no issues.

Left Speaker with deformation at the bottom.

Thanks,
John.

 

[venk61176]

In denon 2310 you can save a custom setting for stereo. Kindly check your settings on 2 ch stereo option.


In pure mode the bass control will be passed on subwoofer. Adjust it by setting it to Lfe + main

Please be careful as in pure mode, your speaker will be treated as full range somebody mentioned. So stick with stereo mode for bass management.

 

[john_k_antony]

Even though you have set your speakers to "Small" & set the crossover to 80Hz, i think Pure direct mode will override all the functions and pass the full range signal to the speaker.....

My Onkyo has "Pure Audio" / Direct mode... Pure audio treats the speakers as full range even though you have set the speakers as "Small"...

You are absolutely right. My bad.. I some how assumed that AVRs will honor the speaker size and do the cross over appropriately .

-John.

 

[john_k_antony]

In denon 2310 you can save a custom setting for stereo. Kindly check your settings on 2 ch stereo option.


In pure mode the bass control will be passed on subwoofer. Adjust it by setting it to Lfe + main

Please be careful as in pure mode, your speaker will be treated as full range somebody mentioned. So stick with stereo mode for bass management.

venk61176,

I think I learnt my lesson the bad way . Its still okay as my speakers are still working fine.

I have a different setting for 2 channel in Denon and I have kept the speakers as Small there as well and also set the cross over at 100Hz. But I don't use my Denon + KEF for 2 channel anyways. I have a different setup for 2 channel stereo. So I guess I am fine as long as I use Denon + KEF only for movies and NEVER EVER use Pure Direct mode for that .

Thanks,
John.